Most homes and many commercial facilities rely on cylindrical locks or mortise locks to provide security at doorways and/or other access points. The dead latch is an essential component of these types of locks. For example, as shown in FIG. 1, a conventional cylindrical lock set 10 may include a latch 12 and dead latch 14, which is the small secondary piece located in front of the latch 12. The lock set 10 also includes typically a keyed knob or handle, for example, provided on the outside of a door and a knob or handle with a push button or twist lock, for example, provided on the inside, the knobs functioning to control the extension and/or retraction of the latch 12 and dead latch 14. The latch 12 and dead latch 14 are each configured to extend into and out from the cylindrical lock set 10, both being spring-loaded toward the extended position.
To use the lock set, a cavity is configured into a door jamb, or another door, for example, in specific alignment with the lock set 10 in order to receive the latch 12. A metal strike plate is typically mounted to the door jamb that guides the latch 12 into the cavity while providing increased strength to the door jamb around the cavity. The lock set 10 is installed in the door such that when the door is closed, the latch 12 and dead latch 14 are both depressed (i.e., retracted into the lock set) while passing over the strike plate until the latch 12 is received through a hole in the strike plate so that the latch 12 is permitted to extend into the cavity. It is critical that the alignment of the lock set 10 and the strike plate are such that when the latch 12 extends into the cavity when the door is closed, the dead latch 14 remains depressed by abutment against the strike plate. The lock set 10 is configured so that when the dead latch 14 is depressed while the latch 12 is fully extended, the latch 12 may not be depressed, preventing someone from using a credit card, for example, to push the latch 12 back from the outside when the door is closed and/or locked. Only use of the unlocked outside knob, for example, and/or the inside knob will allow the latch 12 to be retracted from the cavity into the lock set 10 so that the door may be opened.
As shown in FIG. 2, a conventional mortise lock set 20 may include a latch 22 and a dead latch 24. A handle 26 may be provided on the inside and a keyed lock cylinder 28 on the outside of the door. The latch 22 may be controlled via the handle 26 and/or a key inserted into the keyed lock cylinder 28. When the door is closed, the latch 22 is received into the cavity configured into the door jamb and/or strike plate. As noted above, the strike plate and cavity are configured so that latch 22 is received while the dead latch 24 remains depressed through abutment with a portion of the strike plate. Accordingly, the latch 22 may not be depressed from the outside by a credit card or other tool of the trade for gaining unwarranted access to a building or area. The latch 22 may only be released from the locked position and withdrawn into the lock set 20 via the inside handle 26 and/or a proper key inserted into the lock cylinder 28.
Electric strikes, also known as electric releases or electric release strikes, are part of a locking mechanism conventionally used to control access to buildings or areas, for example. Electric strikes may be used in conjunction with mortise and cylindrical lock sets. An electric strike is typically mounted into a door jamb and receives the latch and/or a dead bolt, for example. As shown in FIG. 3, a conventional electrical strike 30 normally requires a cut in the frame facing the door for mounting the strike. A pivotal keeper 32 in the electric strike may then be used to selectively close the opening in the frame face to prevent or allow release of the door's latch in order to lock the door or allow the door to be opened. When used with cylindrical or mortise type lock systems, the electric strike takes the place of the regular strike plate.
An opening and or cavity 34 for receiving the latch in electric strikes is often much bigger than provided by in the typical strike plate so that an electric strike may work with a variety of lock sets. Moreover, for use with a cylindrical lock set 10, for example, the keeper 32, which is usually only about ⅛″ wide at the point where the latch is received, must be configured to catch the dead latch when the door is closed, preventing the dead latch from also falling into the cavity 34. The combination of the larger cavity 34 and the narrow keeper 32 that must receive the dead latch often make installation difficult in order to align everything precisely so as not to defeat the purpose of the dead latch and create situation where the lock can easily be breached.
There is a need and desire for an electric strike assembly having a configuration that can be easily installed into an existing door jamb without the need to make an entirely new cut in the frame. The electric strike must also be configured to work with existing cylindrical and mortise type locks to ensure that the dead latch function remains viable once installed.